c语言 9-6

1、

#include <stdio.h>

int str_chnum(char x[], int key)
{
    int len = 0;
    while(x[len])
        len++;
    int j = 0;
    while(len-- > 0)
    {
        if(x[len] == key)
            j++;
    }
    if(j == 0)
        return 0;
    else
        return j;
}

int main(void)
{
    char str[128];
    printf("str: "); scanf("%s", str);
    printf("c number: %d
", str_chnum(str, 'c'));
    return 0; 
}

2、

#include <stdio.h>

int str_chnum(char x[], int key)
{
    int len = 0;
    while(x[len])
        len++;
    int i, j = 0;
    for(i = 0; i < len; i++)
    {
        if(x[i] == key)
            j++;
    }
    
    return j == 0 ? 0 : j;
}

int main(void)
{
    char str[128];
    printf("str: "); scanf("%s", str);
    printf("c number: %d
", str_chnum(str, 'c'));
    return 0;
} 

3、

#include <stdio.h>

int str_chnum(char x[], int key)
{
    int i = 0, j = 0;
    while(x[i])
    {
        if(x[i] == key)
            j++;
        i++;
    }
    return j == 0 ? 0 : j;
}

int main(void)
{
    char str[128];
    printf("str:  "); scanf("%s", str);
    printf("c number: %d
", str_chnum(str,'c'));
    return 0;
}

4、

#include <stdio.h>

int str_chnum(char x[], int key)
{
    int i = 0, j = 0;
    while(x[i])
    {
        if(x[i] == key)
            j++;
        i++;
    }
    return j;
}

int main(void)
{
    char str[128];
    printf("str:  "); scanf("%s", str);
    printf("c number: %d
", str_chnum(str, 'c'));
    return 0;
}